A number of patents have proposed various devices for loading multi-tiered carts, but the task of arranging a plurality of articles advancing in a column along a production line by assembling them into compact rows and columns arrayed on the multiple shelves of a rolling cart requires successive staging of two or four or six columns of articles aligned in rows, in order to provide compact loading of each shelf of the multi-tiered cart, and raising or lowering of the cart or the articles is also required in order to align them for loading onto each shelf in turn.
Kampfer U.S. Pat. No. 3,637,095, issued in 1972, shows in FIG. 1 a machine with vertically movable shelves, all collected at the bottom of their stroke at 75 in FIG. 1 of the patent. These shelves are successively loaded at the level of the input conveyor 14 in the patent and then successively raised to positions 71, 72, 73 and 74.
Schroeder U.S. Pat. No. 1,518,278 loads successive pallet trays of bricks, stacked one above the other, on an elevator for transfer to a specialized truck with a series of pallet engaging flanges 110, which unloads the entire elevator in a single step and delivers all of the pallets to a kiln for curing. Carothers U.S. Pat. No. 2,935,908 shows a similar arrayed plurality of forks successively picking up green ceramic tiles from their delivery conveyor and arraying them vertically for glazing and curing.
Several Lindberg hospital tray loading patents show a rolling cart, where successive food trays delivered by a conveyor are arrayed in a vertically reciprocated elevator rack 7. In Lindberg's earliest U.S. Pat. No. 4,032,027, issued in 1977, the arrayed trays are transferred by a pusher 8 or 9 from the elevator to the rolling cart tiers. The later Lindberg U.S. Pat. Nos. 4,203,696 and 4,277,216 show horizontally movable belt drive arms which reach into the cart and remove trays for redelivery to a conveyor leading to the dishwasher, and in the 1981 '216 patent such arms can be used either for loading or unloading the cart.
Grasvoll U.S. Pat. No. 3,594,977, issued in 1971, shows a rolling cart loader for milk cartons which raises the cart 27 successively from one level to another, while rows of milk cartons are assembled on a conveyor plate 8 and then delivered by a pusher 9 and stripper plate 18 to successive shelves of the rolling cart as the cart 27 is moved vertically from level to level by elevator 24. At column 4, lines 61-66, the reversal of this mechanism is suggested, with the cart being fixed and the conveyor plate 8, pusher 9 and stripper plate 18 being moved vertically, but such a reversed mechanism is not illustrated or otherwise disclosed in this Grasvoll patent.
Other patents show many different kinds of vertical conveyor stages, including one for loading tires on a rolling cart, Leblond Uniroyal U.S. Pat. No. 3,696,949, and Temple U.S. Pat. No. 3,584,750 shows racks of bread loaves assembled on an elevator 38 from a delivery conveyor 263 and then all moved together by a pusher 304 onto a multi-tiered rolling cart. Ashford U.S. Pat. No. 2,661,100 shows a bottle-rolling case loader for a rolling cart hoisted on an elevator.
The operations of assembling or "staging" the advancing procession of containers into groups for shelf loading requires momentary interruptions in the procession each time an assembled column is moved sidewise to make room for the succeeding column, and each time the staged rows of columns are moved onto the cart shelves. If these periods of interruption of the advancing procession of containers are minimized, the loading operation is thereby made more efficient.
A further interruption in the normal loading operation often occurs when the cart has been completely filled and must be disengaged from the loading station and rolled away, to permit an empty cart to be rolled into position for loading.
In the Kampfer U.S. Pat. No. 3,637,095 discussed above, five individually elevated shelves are successively filled with containers and raised into positions aligned horizontally with the shelves of an adjacent rolling cart. These elevated shelves are then moved en masse to project into the cart, between the cart shelves, by advancing an entire internal subframe of the overall device, and retainer bars are then held stationary behind the containers as the elevated shelves are withdrawn together, leaving the entire cart fully loaded with containers. If desired, as shown in this patent, the adjacent one-half of each cart shelf may be loaded simultaneously from one side of the cart, and the cart may then be reversed for loading the empty remaining halves of each cart shelf simultaneously by a similar operation. While this Kampfer cart loader thus occupies most of its cycle time in successively loading and raising individual elevated shelves, the complex mechanism required to perform this function and then to move the entire subframe back and forth for each cart loading step requires close tolerances in fabrication and alignment, with many moving parts that may mis-align or jam in operation, and considerable loads must be moved both vertically and horizontally by the drive mechanism.
Kampfer's cart loader is understood to have been manufactured by Ex-Cell-O Materials Handling Co., an affiliate or successor to Conveyor Specialties Co., the assignee of the Kampfer's patent. The same company manufactures a travelling tray cart loader in which trays move in a rectangular path: they are loaded, moved upward, advanced forward across the top of the machine, lowered downward into alignment with the cart shelves, unloaded onto the cart shelves and lowered further for return to the tray loading station, sweeping out a rearward, upward, forward, and downward rectangular path during a full cycle of machine operation. This travelling tray cart loader thus requires a great number of trays and substantial power requirements as well as complex mechanism and the need for a depressed pit below normal floor level or an elevated ramp to raise the empty carts, to permit the return of unloaded trays to the tray loading station.
The cart loaders of the present invention provide many advantages over these conventional prior art cart loader proposals.